Evidence for the first globular cluster stellar stream beyond the Milky Way

Area of Science:

• * Astronomy and astrophysics
• * Cosmology
• * Galaxy evolution

Background:

• * The dark matter content of ultra-diffuse galaxies (UDGs) remains a significant area of debate.
• * Stellar streams, formed by tidal stripping of stars from orbiting systems, are effective probes of galactic dark matter halos.
• * Globular cluster (GC) stellar streams are particularly sensitive to dark matter halo properties but have only been observed in the Milky Way.

Purpose of the Study:

• * To present the first evidence of an extragalactic GC stellar stream.
• * To constrain the dark matter halo of the UDG UGC 9050-Dw1 using this stream.
• * To establish GC stellar streams as a tool for extragalactic dark matter studies.

Main Methods:

• * Deep Hubble Space Telescope (HST) imaging of the UDG UGC 9050-Dw1.
• * Analysis of the stream's morphology and color to support a GC progenitor interpretation.
• * Generative stream modeling to fit dynamical models to stream morphology and constrain progenitor mass.

Main Results:

• * Identification of the first extragalactic GC stellar stream in the UDG UGC 9050-Dw1.
• * Observational evidence supporting a GC progenitor, consistent with simulated stellar populations.
• * First stream-based dark matter halo constraint for a UDG, indicating a massive halo.

Conclusions:

• * The discovery of an extragalactic GC stellar stream opens new avenues for dark matter research.
• * This technique provides a novel method for constraining dark matter in UDGs.
• * The findings suggest that UDGs can host massive dark matter halos.